(1) Field of the Invention
The present invention relates to an access server with the function of collecting communication statistics information and, more particularly, to an access server connected to a user access network and to an Internet service provider network (ISP network) and having the function of notifying an accounting server connected to the ISP network to manage communication statistics information of communication statistics information collected for each user-terminal.
(2) Description of Related Art
In an IP (Internet Protocol) network represented by the Internet, a communication agency (network management agency) which provides the service of connecting a user terminal to the IP network is termed an Internet Service Provider (ISP). The ISP verifies that an access requesting user is an authorized subscribing user prior to the use of an access server by a user terminal and establishes a session between the access server and the user terminal.
As a communication protocol for establishing a session between the access server and the user terminal, PPP (Point-to-Point Protocol) has been used widely. The PPP is originally a protocol for providing a TCP/IP or like link on a serial line such as a telephone line or a dedicated line and has been standardized as RFC (Request for Comments) 1661 at IETF (Internet Engineering Task Force).
The PPP is composed of an LCP (Link Control Protocol) operating in the data link layer of an OSI reference model and an NCP (Network Control Protocol) operating in a network layer. The LCP is a protocol for controlling a link which establishes a data link between two communication devices through a negotiating operation concerning communication conditions such as a data size, the presence or absence of data compression, and a transmission speed and performs a control operation for examining and releasing the data link. On the other hand, the NCP performs, after the establishment of a link (LCP session) in accordance with the LCP, the selection of a higher-layer protocol for the network layer, the allocation and setting of a network address and the like. For the NCP protocol, a plurality of control protocols are prepared depending on the type of a network protocol so that the NCP protocol is adaptable to various protocols such as IP and AppleTalk.
An ISP stores personal information on users and statistics data as attribute values in a database, which is managed in a unified manner by, e.g., a management server such as an authentication server or an accounting server. The management server is normally communicative with an access server on the Internet via an IP network. For session management between these servers and between the access server and a user terminal, the RADIUS (Remote Authentication Dial In User Service) is used normally. Communication protocols concerning the RADIUS are defined as, e.g., the RFC 2138, the RFC 2139, the RFC 2865, the RFC 2866, and the RFC 2869.
The RADIUS has adopted a server client system which operates the server for managing the attribute information such as the user information and the statistics information described above as a RADIUS server and operates an access server for accepting access from a user as a RADIUS client, thereby enabling the transmission and reception of attribute information between the access server and the RADIUS server.
The first role of the RADIUS server is the management of user authentication information. For example, the access server having received an Internet access request from a user terminal extracts user authentication information including a user name and a password from the access request and transmits the extracted information to the RADIUS server in accordance with the RADIUS authentication protocol. Upon receiving the user authentication information from the access server, the RADIUS server judges whether the requester is an authorized subscribing user or not by comparing the received user authentication information with user authentication information preliminarily registered in the database and notifies the access server of the result of judgment. If the access requesting user has proved to be an authorized user as the result of authentication, the access server executes a connection control operation for a PPP session between the user terminal and the access server.
The second role of the RADIUS server is the management of statistics information for each user. When the user authentication and the PPP connection are completed successfully, the access server transmits a control packet indicating that the user has started the Internet use to the RADIUS server and starts to collect statistics information on the user. When the user has terminated a data link, the access server transmits a control packet indicative of the release of the link (termination of the Internet use) to the RADIUS server. The control packet includes an identifier (ID) for identifying the user and notifies the RADIUS server of the statistics information including, e.g., a PPP link session time and an amount of communicated data. Using the RADIUS functions described above, a majority of ISPs perform user authentication and collect management information for accounting and a network extension plan.
With the recent increase in the number of Internet users, a dual stack network which allows the use of the IPv6 having a new address system in addition to the existing IPv4 has been constructed. To use the IPv6 on the PPP, it becomes necessary to equip the NCP with a control protocol for the IPv6 and define attributes for the IPv6 for the RADIUS. As the control protocol for the IPv6, the RFC 2472 has already defined the IPv6CP, while the RFC 3162 has defined the IPv6 support attributes for the RADIUS as the attributes for the IPv6.
An IP version to be used on the PPP is specified by the attributes of a response packet (authentication success packet) returned from the RADIUS server to the access server in response to an authentication request. That is, by transmitting only IPv4-related attributes, only IPv6-related attributes, or attributes related to each of the IPv4 and the IPv6, the RADIUS server can notify the access server that a usable IP protocol is the IPv4, the IPv6, or the IPv4/IPv6, respectively.
On the other hand, the NCP can be operated independently at each user terminal. Each user is allowed to establish an arbitrary NCP at any time and release the NCP at any time during a period after the establishment of a link in accordance with the LCP till the release of the link. User management is performed by using IDs unique to each of links (LCP sessions) set in the access server. Accordingly, when a plurality of NCP sessions are established on a PPP as described above, it has conventionally been impossible to collect statistics information such as a session time and an amount of data on a per NCP basis, though it was possible to individually collect the statistics information on each of links (LCP sessions) established in accordance with the LCP.
As a prior art technology related to the collection of communication statistics information, Japanese Laid-Open Patent Publication No. 2000-16337 (Patent Document 1) proposes a traffic monitoring system which determines the type of a protocol used for an IP packet, e.g., the use of electronic mail or the Web by analyzing the header of the IP packet, individually measures a communication time from the first packet to the final packet for each of the protocols in use, and records the measured communication time as a per-protocol based session time for each of the users.
On the other hand, Japanese Laid-Open Patent Publication No. 2000-252979 (Patent Document 2) proposes a connection system between a CATV network accommodating therein a larger number of user terminals and the Internet, wherein a data amount probe unit determines the address of a transmitter, an amount of data, the type of a protocol (including the type of data) from the contents of the header of an IP packet to be transferred and notifies a data amount summing unit of the determined information via an internal bus so that the data amount summing unit individually sums up statistics data for each of IP addresses and for each of protocols.